Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany.
Water Res. 2013 Feb 1;47(2):769-80. doi: 10.1016/j.watres.2012.10.051. Epub 2012 Nov 15.
For several pilot-scale constructed wetlands (CWs: a planted and unplanted gravel filter) and a hydroponic plant root mat (operating at two water levels), used for treating groundwater contaminated with BTEX, the fuel additive MTBE and ammonium, the hydrodynamic behavior was evaluated by means of temporal moment analysis of outlet tracer breakthrough curves (BTCs): hydraulic indices were related to contaminant mass removal. Detailed investigation of flow within the model gravel CWs allowed estimation of local flow rates and contaminant loads within the CWs. Best hydraulics were observed for the planted gravel filter (number of continuously stirred tank reactors N = 11.3, dispersion number = 0.04, Péclet number = 23). The hydroponic plant root mat revealed lower N and pronounced dispersion tendencies, whereby an elevated water table considerably impaired flow characteristics and treatment efficiencies. Highest mass removals were achieved by the plant root mat at low level: 98% (544 mg m⁻² d⁻¹), 78% (54 mg m⁻² d⁻¹) and 74% (893 mg m⁻² d⁻¹) for benzene, MTBE and ammonium-nitrogen, respectively. Within the CWs the flow behavior was depth-dependent, with the planting and the position of the outlet tube being key factors resulting in elevated flow rate and contaminant flux immediately below the densely rooted porous media zone in the planted CW, and fast bottom flow in the unplanted reference.
针对受 BTEX、燃料添加剂 MTBE 和铵污染的地下水，采用时间矩分析方法对几种小规模人工湿地（有植物和无植物砾石过滤器）和水培植物根垫（两种水位条件）的出水流体示踪突破曲线（BTC）进行了水力特征评估：水力指数与污染物去除量相关。通过对模型砾石人工湿地内部流动的详细研究，估算了人工湿地内的局部流速和污染物负荷。有植物的砾石过滤器表现出最佳的水力性能（连续搅拌罐反应器数 N = 11.3，弥散数 = 0.04，佩克莱数 = 23）。水培植物根垫的 N 值较低，弥散趋势明显，而高水位极大地影响了水流特性和处理效率。在低水位条件下，植物根垫的去除率最高：分别为 98%（544mg m ⁻² d ⁻¹ ）、78%（54mg m ⁻² d ⁻¹ ）和 74%（893mg m ⁻² d ⁻¹ ），对苯、MTBE 和铵态氮而言。在人工湿地内，水流特性随深度而变化，种植和出水管位置是导致有植物人工湿地根部密集多孔介质区下方流速和污染物通量升高以及无植物参照区底部快速流动的关键因素。
